1. Field of the Invention
The present invention relates to a dispenser for storing and automatically dispensing fluent materials.
More particularly, the present invention relates to a dispensing apparatus featuring a thermomagnetic mechanism which when actuated causes fluid materials stored in the apparatus to be dispensed in predetermined amounts under a preset timing.
The present invention may be advantageously used in, but is not limited to use in, clothes washing machines and dishwashers for automatically adding detergents and rinse aids during the operating cycles thereof.
2. Description of the Related Art
Detergent and rinse aid dispensers for use in household and industrial washing machines, to which reference will be made by way of example hereinafter, are widely known in the prior art.
These prior art dispensers have various types of actuating means for automatically dispensing detergent and/or rinse aid. These actuating means in turn adopt various release mechanisms to displace or release a single part or a subassembly of the dispenser under the command of a typically electric control mechanism.
Usually detergent is stored in an appropriate reservoir in the dispenser. A gate or lid acts to confine the detergent within the reservoir. When the detergent is required to be dispensed, an electric pulse is issued to the gate or lid so as to open the same, thereby enabling the detergent to flow into the washing tub or tank.
Similarly, rinse aid is confined in an appropriate reservoir by an electrically actuatable valve. Therefore, when the rinse aid is required to be dispensed, an electric pulse is issued to the valve causing the valve to open so that the liquid rinse aid is allowed to flow into the washing tub or tank.
There are primarily three types of actuating means used in the prior art to carry out the above-described functions:
(a) electromagnetic, whereby actuation is effected by the displacement of a movable iron core in a solenoid when an electric pulse is issued thereto;
(b) thermomechanical, whereby the actuation occurs through the displacement of a pin extending from an enclosure filled with wax with a water-tight seal established therebetween; the wax is expanded to move the pin by raising the temperature of the wax with a thermistor, a PTC (Positive Temperature Coefficient) device, or an electric heating element;
(c) bimetal element, whereby the actuation occurs by heating the bimetal element with an electric heating element, a PTC device or a thermistor.
Electromagnetic systems are quite expensive. Furthermore, they are prone to failure to due to winding faults and they can be quite noisy (clattering) during operation.
Thermomechanical systems are also expensive and may experience defects in the water-tight seal between the pin and wax-filled enclosure.
On the other hand, bimetal systems are relatively simple. However, they are subject to a number of application-related problems, since their component parts are sensitive to room temperature and other variable conditions.